Thermally Stable, Flexible Substrates for Electronic Devices

1. A substrate for use in or with electronic devices, wherein the substrate comprises: an organo-soluble polyimide film having an out of plane birefringence of less than about ±0.002, wherein the organo-soluble polyimide has a glass transition temperature greater than about 300° C. and is comprised of: an alicyclic dianhydride selected from the group consisting of: 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; and at least one aromatic cardo diamine selected from the group consisting of 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-fluorophenyl)fluorene, and 9, 9-bis(4-amino-3-methylphenyl)fluorene; and wherein: the film is flexible and has a thickness of less than about 50 microns and a transmittance of greater than about 80% at about 400 nm to about 750 nm both before the film is heated and after the film is heated to 300° C. for no longer than 60 minutes.

2. The substrate of claim 1 , wherein the electronic device is a flat panel display, a lighting device, a photovoltaic device, or an input/output device.

3. The substrate of claim 1 , wherein the film has a thickness of at least 25 microns.

4. The substrate of claim 1 , wherein the film has a coefficient of thermal expansion of less than about 60 ppm/° C.

5. The substrate of claim 1 , wherein the polyimide further comprises an aromatic dianhydride.

6. The substrate of claim 1 , wherein the polyimide further comprises a non-cardo, aromatic diamine.

7. A substrate for use in or with electronic devices, wherein the substrate consists essentially of: a single polymer layer having a thickness of less than about 50 microns comprising: an organo-soluble polyimide having a glass transition temperature greater than about 300° C. and an out of plane birefringence of less than about ±0.002, wherein the organo-soluble polyimide comprises at least one alicyclic dianhydride selected from the group consisting of 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, and bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride; and at least one aromatic cardo diamine selected from the group consisting of 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-fluorophenyl)fluorene, and 9, 9-bis(4-amino-3-methylphenyl)fluorene; and a glass layer; wherein the single polymer layer has a transmittance of greater than about 80% at about 400 nm to about 750 nm both before and after it has been exposed to 300° C. for no longer than 60 minutes, and is flexible.

8. The substrate of claim 7 , wherein the single polymer layer has a thickness of at least 2 microns.

9. The substrate of claim 7 , wherein the glass layer has a thickness of at least 20 microns.

10. The substrate of claim 7 , wherein the single polymer layer has a coefficient of thermal expansion of less than about 60 ppm/° C.